The present invention relates to a camera in which a film cartridge with a bar code disk having a bar code which shows film information such as the film sensitivity, the number of exposable frames of the film, etc., is loaded. Further, the present invention relates to a camera with a film feeding mechanism in which the film is wound up by a reel when a camera motor is rotated normally, and the film is re-wound by a spool provided in a cartridge when the motor is rotated reversely.
Relating to reading out the bar code from the film cartridge with a bar code disk having thereon a bar code which shows film information such as the film sensitivity, the number of exposable frees of the film, etc., the following method has been disclosed in Japanese Patent Publication Open to Public Inspection No. 215630/1992: a method in which the bar code is read out during steady rotation of the spool after a predetermined time has passed after the rotation of the spool has started. Further, in a pre-winding type camera in which all the film is wound up before the start of picture-taking, a method, in which the bar code is repeatedly read out during the pre-winding operation, and after that, data having the same information, which most frequently appears among read-out data, is adopted as correct data, has been disclosed in Japanese Patent Publication Open to Public Inspection No. 53187/1993.
However, the rotational speed of the spool is not constant due to various factors caused by the driving system of a camera, loads of the loaded cartridge, etc. Accordingly, a serious problem occurs when the bar code is erroneously read, resulting in reading of erroneous information. Further, there is also a problem in which information can not be repeatedly read while three exposed frames are fed in a short period of time until the first available exposable frame is ready, in a camera in which the film is normally wound up so as to expose the film from the first exposable frame.
In order to solve the foregoing problems, the present inventors have proposed the following method in Japanese Patent Application No. 328191/1993: film information can be positively read out even when the degree of rotation of the spool driving shaft is greatly changed, when the film information is read out from the bar code on the bar code disk rotated in synchronization with reference signals outputted in a predetermined rotational period corresponding to the rotation of the spool driving shaft.
However, in the prior patent application of the present inventors, a detection means is necessary for detecting the engagement of the spool of the cartridge with the driving shaft of the spool of the camera. When this detection means is not provided, the following problems occur. The spool shaft is rotated by the motor when the rear cover of the camera is closed after a cartridge is loaded into the camera. Reference signals are outputted corresponding to the rotation of the driving shaft of the spool although the driving shaft of the spool is not yet engaged with the spool. That is, although the bar code is stopped, the stopped bar code is read out as if the bar code having the same pattern continues. As a result, a read-out reference position of the bar code is erroneously read out, and erroneous information is read out, which is a problem.
Specifically, when a film cartridge, in which a condition of use of the film is judged by the rotational angle of the spool, is used in a camera, an engaged position of the spool with the spool driving shaft is limited in the rotational direction, and an excessive period of time is necessary for the engagement of the spool with the spool driving shaft. Accordingly, the foregoing problem occurs more easily.
In order to realize a low cost camera even when the foregoing cartridge is used, the first object of the present invention is to propose a camera in which erroneous film information is never read out just after the rotation of the spool starts as described above without providing the above-described detecting means.
In this connection, the following gears have been disclosed in Japanese Patent Application No. 4835/1994 applied by the present inventors: a reversible motor; reel driving gears; spool driving gears; planetary gears which drive the reel driving gears at the time of film winding up, and which are disengaged from the reel driving gears at the time of film re-winding; planetary gears Which drive the spool driving gears during film winding up, and which are disengaged from the spool driving gears during film re-winding; and planetary gears which drive the spool gear during film re-winding, and which are disengaged from the spool gear during film winding up.
When the motor starts normal rotation and is switched to wind up the film in the case where the film is under the re-winding condition, using the film feeding mechanism disclosed in Japanese Patent Application 4835/1994, the following problems were found by the present inventors. That is, when the planetary gears for driving the reel driving gears at the time of film winding-up are engaged with the reel driving gears before the planetary gears which have been driving the spool gear during film re-winding are disengaged from the spool gear, then, the reel driving gears drive the reel, the reel winds up the film, and then the film rotates the spool, that is, the spool gear. As a result, the planetary gears which have been driving the spool gear during film winding-up can not be disengaged from the spool gear, the force is supplied to the planetary gears from two driving sources of the spool gear and the sun gear, and finally, the motor is forced to stop. The second object of the present invention is to propose a camera which can be solve the above-described problems.